A couple Protestants have objected to it in the comments. The first one says, apparently because he believes that this has some significant weight for the topic:
However, let us be clear on one point - Protestants didn’t leave the Roman church. They were excommunicated.Okay, that's fine. But they weren't excommunicated in a vacuum, as though there was no reason for it, were they? I'm not the sharpest tool in the shed, but if a man denies the doctrines taught by the Church, it seems to me that he has already excommunicated himself. All that might remain is for it to be formally declared. You can't reasonably call yourself a Baptist if you deny the Baptist view of baptism; you can't reasonably call yourself a Presbyterian if you reject the authority of the WCF (or of some cross-section of its contents sufficient to be called a transgression of the "system of doctrine" taught therein). In the same way, by definition you cannot be Catholic if you deny Catholic doctrine. So really, "being clear" on this point doesn't seem to my small brain to have a thing to do with the question of "The Foundational Difference Between Catholics and Protestants."
Perhaps this poster intends the rest of his post to explain things, but I don't see how.
So, in effect, we have some really short-sighted members of the Roman hierarchy in the 16th century to thank for the proliferation of ‘churches’ (of course, we could trace this back further to the Great Schism, various breaks occurring in connection to various of the great ecumenical councils, and beyond - this myth of a monolithic church prior to the Reformation is just that, a myth).Again: I'm not sure what this has to do with the present subject. Those who reject Catholic doctrine cannot reasonably be called Catholics. The Church did not compel them to err. They did so on their own. The Church remains what she has always been - namely, The Church - regardless of the predilections of those who decide that they know better than the totus Christus (CCC 795) what the truth is.
Then, even more peculiarly, the poster concludes:
[people feeling free to ‘leave their church’] certainly isn’t a theological tenant in the Reformed tradition, as long as the church under consideration remains a church, i.e. a place where the Word of God is properly preached and heard and the sacraments are administered according to Christ’s institution.But this is precisely A Thomist's point, so it completely escapes me how this is supposed to be a defense against the article's observation (and it really isn't what I would call an "attack piece," but rather seems to me to be presented more as an analysis. A Thomist is not generally - from what I've seen - given to polemics for polemics' sake): for the Catholic, the Church cannot stop being The Church. Protestants hold to no such view, precisely because they have an abstract notion of what "the Church" is.
It's worth pointing out that the poster's description of what conditions must prevail in the Reformed tradition in order to legitimize leaving one's congregation or denomination isn't exactly a commonly held viewpoint today...nor in the history of the Presbyterian denominations, to my knowledge. In the first place, while the WCF does say that the marks of "the true church" are preaching of the Word, church discipline, and proper administration of the sacraments, it doesn't indicate in any way who is competent to judge whether these "marks" are present or not. Also absent is any specification of the actions that must be taken in case they are judged by this unidentified authority to be missing from some ecclesiastical structure.
Secondly, recent history at least seems to suggest that what he says is not the case. The Bible Presbyterians broke away from the Orthodox Presbyterians over the issue of alcohol consumption. The OPC refused to unite with the PCA back in the 1980s, and I still don't know why. It wasn't because they didn't share a confessional bond (they did); it wasn't because they thought the PCA wasn't a "true church" (they didn't think this, either). I'm sure they didn't mean to be merely arbitrary, but I sure don't understand what objective grounds they thought they had: if disunity is a scandal, why would they refuse proffered unity with a group they acknowledge as brothers and sisters in Christ sharing even the same confessional standards? Hence it seems that A Thomist's critic is not fairly representing his own tradition in this respect.
In the third place, and having been a Presbyterian for over 20 years, I can safely say that I don't recall ever having seen such a standard ("a man shouldn't leave a church unless the marks of the church are absent") being enforced by a Session or Presbytery in the PCA. Indeed, quite the contrary: I know of at least one case in which a congregation was practically invited to leave a presbytery, and I never heard of anyone being subjected to discipline for having left a congregation (or even the denomination) on the grounds that they had no cause for it.
Lastly, and to wrap this up, this same poster makes a Platonic appeal to try and bolster his position:
Surely you or I cannot create a universal or an abstract entity, but the same one who created “roundness” could certainly create a Church which exists independently of any particular manifestation.Nothing more needs to be said here than that Aristotle and St. Thomas have adequately refuted this. The forms have no actual existence apart from the concrete.